(1) Field of the Invention
The present invention relates to a novel spiro-oxazine compound which is valuable as a photochromic material for printing and photography, a photochromic material for optical devices, a photochromic material for recording media and a photochromic material for clothings and decorative articles
(2) Description of the Related Art
As a typical instance of photochromic compounds, there can be mentioned a spiropyran compound, and there are known a variety of compounds of this type [G.H. Brown, "Photochromism", Wiley Interscience, New York (1971)].
As the photochromic spiro-oxazine compound, 1,3,3-trimethylspiro [indoline-2,3'-[3H]-naphtho[2,1-b](1,4)-oxazine] and substituent derivatives thereof are disclosed in U.S. Pat. Nos. 3,578,602, 3,562,172 and 4,215,010 and Japanese Unexamined Patent Publication No. 48-23787.
Spiropyran compounds exhibit poor fatigue resistance when used repeatedly for coloration and decolorization. The known spiro-oxazine compounds have improved fatigue resistance over the spiropyran compounds, but coloration by exposure to light or by irradiation is limited to blue. Both of them are at least partially decomposed to non-photochromic compounds or colored compounds when they are brought into contact with an acid substance.